Private Well

A rig bores the hole and sets steel or plastic casing so the walls cannot cave in. A submersible pump hangs below the standing water level. It sends water to a pressure tank near the house, which holds a reserve under air pressure so the pump does not restart every time you open a tap. Arizona requires a licensed well-drilling contractor, and ADWR gives the finished well a registration number that starts with 55.

Depth is the number nobody can quote up front. It follows the basin, and Arizona is a state of basins. ADWR publishes what nearby wells found, through its Wells 55 map and its Groundwater Site Inventory. A careful driller reads those logs for your road before pricing, because drilling and casing sell by the foot. Two lots a mile apart can be a modest well and a punishing one.

The ongoing duty is what buyers underestimate. State health officials put it plainly: private well water is not tested or regulated by any government organization, so the owner is the only one watching. ADHS says to test a new well for arsenic, coliform bacteria, fluoride, lead, nitrates, dissolved solids, and uranium. Then coliform and nitrates yearly, and arsenic, fluoride, and uranium every five years.

For example, a buyer on unincorporated land near Rio Verde Foothills should pull the well log and the last water-level reading before closing, then budget for a pump replacement. A lot with no producing well ends up on trucked hauled water into a cistern instead. If a neighbor offers to share a well, note that ADWR does not regulate shared well agreements and will not step into a dispute.

A private well is the physical system. An exempt well is the legal label the state puts on a small one, based only on the pump rating. Most single-family wells carry both descriptions, so the paperwork question and the water question get answered separately.